1. Field of the Invention
The invention relates to an optical head and an image forming apparatus using the optical head.
2. Related Background Art
In an LED (Light Emitting Diode) printer, that is, electronic photograph printer serving as an image forming apparatus, using an LED head as a writing-in light source, an exposing process is performed. In the exposing process, the light produced by the LED array chip serving as an emitting light section is converged through a rod lens array with convergency, i.e., self focusing lens array (hereinafter: SLA) serving as a light guide section. Then, an electrostatic latent image is formed by exposing the light to a photo conductor drum which is placed at a position with light image-formation and is all charged with electricity.
FIG. 2 is a perspective view showing a conventional LED head; FIG. 3 is a front view showing the conventional LED head; FIG. 4 is a first cross-sectional view showing the conventional LED head; and FIG. 5 is a second cross-sectional view showing the conventional LED.
In FIG. 4 and FIG. 5, 11 is an LED array chip, 12 is a SLA, 13 is a substrate on which LED array chip is installed, 14 is an SLA holder i.e. a holder for holding the SLA 12 and mounting the substrate 13, and 15 is a base for sandwiching the substrate 13 together with the SLA holder 14. The base 15 is formed from metal material and is fixed by frictional force between itself and the SLA holder 14.
The SLA holder 14 serves as a frame of an LED head, and is formed as one body by die-casting which uses metal material, for example, Aluminum, which is soured into a mold. With respect to such an SLA holder 14, because 4 its outer surface is in a natural state, i.e., it is not processed, the outward appearance will be not beautiful; further, because its inter surface needs to inhibit the reflection of the light produced by the LED array chip 11 on itself and to insulate from the substrate 13, in general, the outer surface and the inner surface are painted with a black insulating material.
Because the SLA holder 14 is a metal-made member, as shown by FIGS. 2 and 5, for making it obtain an earth, one end of an earth line 18 is fixed on the SLA holder 14 via a metal-made screw. The other end of the earth line 18 is connected with a FG (frame ground) in the image forming apparatus, which is not shown by the figures. Also, the base 15 is a metal-made member, as shown by FIGS. 2 and 4, and is connected to the FG via a pair of metal-made coil springs 24a and 24b that are installed at two ends of the base 15. Thus, it can obtain an earth.
Moreover, the LED head with the above structure, as shown by FIG. 3, is placed to face a photo conductor drum 16. The photo conductor drum 16 is placed in an ID (image drum) unit in the image forming apparatus, which is not shown by the figures.
Further, the features 23a and 23b shown by FIG. 3, are two eccentric cam mechanisms for regulating the distance between the radiant surface (in FIG. 3: the under surface) of the SLA 12 and the surface of the photo conductor drum 16, they are respectively mounted on the bottoms at two sides of the SLA holder 14. Thus, by adjusting the eccentric cam mechanisms 23a and 23b, the distance between the radiant surface of the SLA 12 fixed on the SLA holder 14 and the surface of the photo conductor drum 16 can be regulated.
The LED head gets a spring force towards the photo conductor drum 16 (in FIG. 3: the downward direction) from the coil springs 24a and 24b. On the surface of the photo conductor drum 16, two spacers 25a and 25b are mounted. The eccentric cam mechanism 23a and 23b contact with the spacers 25a and 25b. Thus, the distance between the radiant surface of the SLA 12 and the surface of the photo conductor drum 16 is kept at a definite value, for example, IO. Then, it is possible to perform the printing through using light to form an image on the surface of the photo conductor drum 16.
However, in the conventional LED head stated above, because the SLA holder 14 is a metal-made member, for obtaining an earth, as stated above, it is necessary to fix the earth line 18 on the SLA holder 14 by the metal-made screw 19. Because of this, when installing the LED head into the image forming apparatus, or removing the LED head from the image forming apparatus, a screwing process or unscrewing process becomes necessary. Thereby, the assembly efficiency and the disintegration efficiency of the LED head are lower. Further, because the earth line and the screw are necessary, the cost of the LED head is higher.
To solve the conventional problems as mentioned above, the present invention supplies an optical head with higher assembly efficiency, higher disintegration efficiency and lower cost, and an image forming apparatus using the optical head.
According to the invention, there is provided one optical head comprising:
a holder with electroconductivity which has a insulating cover and supports a light guide section;
a substrate which is mounted in the Holder and is used for installing a Emitting light section;
a base with electroconductivity used for fixing the substrate at the holder; and
a clamp with electroconductivity which presses and contacts the base,
wherein the clamp, while mounted onto the Holder, scrapes off contact part of the insulating cover.
In the one optical head, the clamp has a tip portion with sharp wave shape; the holder and the base are conducted electrically through the clamp; and the holder with electroconductivity is indirectly connected with a frame ground in image forming apparatus.
Further, in the optical head, the light guide section may be lens; the emitting light section may be LED; and the insulating cover may be reflection inhibition member for inhibiting the reflection of light.
According to the invention, there is provided other optical head comprising:
a holder with electroconductivity which supports a light guide section;
a substrate which is mounted in the holder and is used for installing a Emitting light section; and
a base with electroconductivity used for fixing the substrate at the holder;
wherein the base presses and contacts electrically with the most basic surface of the holder.
In the other optical head, the base presses and contacts electrically with the basic surface of the holder at the positions being away from the light guide section; the base has projecting part formed at end thereof; and the holder with electroconductivity is indirectly connected with a frame ground in the image forming apparatus.
Further, in the optical head, the light guide section may be lens; and the emitting light section may be LED.
According to the invention, there is provided one image forming apparatus for forming an electrostatic latent image, comprising:
a optical head used for exposing light to a photo conductor, wherein, the optical head includes:
a Holder with electroconductivity which has a insulating cover and supports a light guide section;
a substrate which is mounted in the Holder and is used for installing a Emitting light section;
a base with electroconductivity used for fixing the substrate at the holder; and
a clamp with electroconductivity which presses and contacts the base, wherein the clamp, while mounted onto the holder, scrapes off contact part of the insulating cover.
In the one image forming apparatus, the clamp has a tip portion with sharp wave shape; and the holder and the base are conducted electrically through the clamp.
According to the invention, there is provided other image forming apparatus for forming an electrostatic latent image, comprising:
a optical head used for exposing light to a photo conductor, wherein, the optical head includes:
a holder with electroconductivity which supports a light guide section;
a substrate which is mounted in the holder and is used for installing a Emitting light section; and
a base with electroconductivity used for fixing the substrate at the holder;
wherein the base presses and contacts electrically with the most basic surface of the holder.
In the other image forming apparatus, the base presses and contacts electrically with the basic surface of the holder at the positions being away from the light guide section, and the base has projecting part formed at end thereof.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.